Mg-5Al-1.5Ca-0.4Zn基镁合金的等温法半固态压铸组织和性能  

Microstructure and properties of Mg-5Al-1.5Ca-0.4Zn based alloyby semi-solid isothermal heat-treatment-die-pressure-casting process

作　　者：杨光昱[1] 郝启堂[1] 介万奇[1] 王武孝[1] 贾文平[1] 

机构地区：[1]西北工业大学材料科学与工程学院,西安710071

出　　处：《中国有色金属学报》2005年第4期614-620,共7页The Chinese Journal of Nonferrous Metals

基　　金：国家重大基础研究发展规划资助项目(G2000067202)

摘　　要：研究了Mg25Al2115Ca2014Zn2012Mn2Sr2Ti合金的等温法半固态压铸组织和性能。结果表明:合金相组成为α(Mg)、(α(Mg)+Al2Ca)共晶和少量球状Mg17Al12。Sr变质合金在585℃等温法处理时,α(Mg)首先分离成核。随着等温时间加长,α(Mg)由块状向球状转变。25min时,转变为粒径40μm的均匀球状组织。此后,球晶发生长大,进而聚拢合并。合金等温法压铸实验发现,组织为均匀细小等轴晶,粒径25μm。合金室温和高温强度较砂铸大幅提高,塑性略有下降。这是由于细晶强化作用,以及晶粒细化使得晶界上半连续分布的Al2Ca相更弥散,这样Al2Ca高温下钉扎晶界的作用更加突出。等温法半固态压铸合金200℃的高温强度优于AZ91压铸合金,可达140MPa。The microstructure and properties of Mg-5Al-1.5Ca-0.4Zn-0.2Mn-Sr-Ti magnesium alloy by semi-solid isothermal heat-treatment-die-pressure-casting process were studied. It is found that there are three main phases formed in the experimental alloy, i.e., α(Mg), (α(Mg)+Al_2Ca) eutectic and Mg_(17)Al_(12). When the alloy modified by Sr is heat-treated at 585℃, the primary α(Mg) phase divorces into lumps. Then the lumps evolve into spheroids gradually with isothermal time increasing. After treated for 25min, the well-distributed spheroidic semisolid-structure with the average grain diameter of 40μm is formed, then the spheroids agglomerate and coalesce. It is also found that the room temperature mechanical properties are improved greatly by semi-solid isothermal heat-treatment-die-pressure casting process. The elevated temperature strength of experimental alloy at 200℃ is up to 140MPa, better apparently than that of AZ91 die-casting alloy. Homogeneous equiaxied fine grains with the average grain diameter of 25μm are obtained in experimental alloy by the semi-solid isothermal heat-treatment-die-pressure casting process.

关 键 词：半固态等温热处理 半固态压铸 显微组织 力学性能 镁合金 

分 类 号：TG146.22[一般工业技术—材料科学与工程] TG146.4[金属学及工艺—金属材料]